1. Field of the Invention
The present invention relates to a cleaning blade, and more particularly, to a cleaning blade used for an electrophotographic apparatus. It also relates to an electrophotographic apparatus making use of the cleaning blade.
2. Related Background Art
The cleaning blade is a plate-like molded product mainly comprising a polyurethane elastomeric material. When applied to an electrophotographic photosensitive member, the cleaning blade is used for the purpose of physically cleaning and removing the toner adhered to the surface of the photosensitive member, by bringing the blade into contact with the surface. In such an instance, however, the blade must resist the electrostatic attraction force of toner particles, exerted to the surface of the photosensitive member, before it can remove the toner particles from the surface of the photosensitive member. Hence, it must be pressed against the surface of the photosensitive member with a great pressure. Thus, a great frictional force is produced between the photosensitive member and the cleaning blade, and therefore it may occur that the cleaning blade is turned and reversed, resulting in no drive of the photosensitive member or no cleaning operation, or that the surface of the photosensitive member is scraped when it is made of a soft material, bringing about defective images or a short life of the photosensitive member. Particularly at the stage of its initial use, the drum surface is so smooth that adhesion may occur between the drum surface and the blade, tending for the blade to be turned over.
To solve such problems, measures have been hitherto taken such that powder of fluorocarbon resin such as PTFE or PVDF is applied to or incorporated into the top of a blade in order to prevent the turnover at its initial use. However, the method in which the fluorocarbon resin powder is applied to the top of the blade has been involved in the problem that an electrical memory remains on the photosensitive drum to cause formation of a defective image at the initial stage. In the instance where the fluorocarbon resin is incorporated into the top of the blade, problems may arise such that the fluorocarbon resin falls off in the course of cleaning because of an insufficiency of the retension power of rubber to the fluorocarbon resin, so that the toner may slip through the part at which the resin has fallen off, resulting in lowering of the cleaning performance.